[请教]BIOS地址映射?

暴雪

原512K的ROM，现换了一个1M的ROM，windows下在 0xFFF0 0000~0xFFF7 FFFF 可以看到追加的512K的内容。
2 U( B# c1 T' c' l6 S但在启动计算机时(BIOS没有初始化计算机），无法访问追加的512K的ROM。
# ]( y& ~$ w. F- N8 x(可以访问原512K的ROM 0xFFF8 0000~0xFFFF FFFF)
: Y& s8 ^# b+ O
我的计算机用的是intel的ICH7南桥。
) H0 v* ?# {  r. n& A6 M在手册上
& ~" \5 M: r3 e6 A( A) {FWH_SEL2—Firmware Hub Select 2 Register (LPC I/F—D31:F0)
FWH_70_IDSEL — R/W. IDSEL for two, 1-M Firmware Hub memory ranges.
  u- X! y+ ^" K9 S5 P) GThe IDSEL programmed in this field addresses the following memory ranges:
2 |0 S7 d! H" ]0 sFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
在这里 IDSEL 如何理解。
) R5 E7 B( t5 r% rFWH_DEC_EN1—Firmware Hub Decode Enable Register
- R3 O2 H! d- U3 H3 D+ `, x(LPC I/F—D31:F0)
FWH_70_EN — R/W. Enables decoding two 1-M Firmware Hub memory ranges.
) m6 S* o; J1 h  q0 X0 = Disable.
1 = Enable the following ranges for the Firmware Hub
- c, P5 A8 F3 u. a1 xFF70 0000h – FF7F FFFFh
FF30 0000h – FF3F FFFFh
除了上面的数据区域，还有其它的数据区域控制ROM到内存地址的映射吗？

谢谢大家了！！！

xtdumpling

IDSEL是LPC spec的一个信号(Device Select),
' ~9 R' `4 x2 o# E) A5 V* tThis one clock field is used to indicate which of multiple Firmware components is being selected.
The four bits transmitted over AD[3:0] during this clock are compared with values strapped onto
pins on the Firmware component. If there is a match, the Firmware component will continue to
decode the cycle to determine which bytes are requested on a read or which bytes to update on a
write. If there isn’t a match, the Firmware component may discard the rest of the cycle and go into
; P% F. f$ s  V2 }8 V1 l& C8 {) Va standby power state.

详见LPC spec:
http://www.intel.com/design/chipsets/industry/25128901.pdf
8 {! c& ]/ T7 C$ a2 P" v. l  D
在ICH 7 中似乎就这几个吧(FWH_SEL1,FWH_SEL2,FWH_DEC_EN1,BIOS_CNTL),据我现在知道的.